Infantry and armored divisions bore the burden of the land fighting in World War II. They came to number 82 out of the 89 divisions mobilized. Other types of divisions will be discussed in less detail. The discussion will overlap somewhat into the third period as defined in the present study, the period when theater experience became dominant in matters of tactical organization.

Motorized, cavalry, airborne, mountain and light divisions were in varying degree experimental, more so than infantry and armored divisions which were experimental in the sense that all military organizations are constantly subject to the test of battle. All these types were infantry divisions in substance, differing from standard infantry chiefly in their means of transport to the scene of combat.

The cavalry division may seem an exception. Far from being a novel experiment, the cavalry division was an old organization, and its cavalrymen remained in principle horsed, not mechanized.122 The Russians made successful use of horse cavalry, and American commanders declared that they could have used it in the difficult terrain of

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Tunisia and Italy. But transportation of horses was so costly in ship tonnage, and their feeding and upkeep presented such difficulties to an Army geared to motors, that no plans were made for shipment of cavalry divisions with their mounts. Of the two divisions mobilized, the 2d Cavalry Division, a Negro unit, was in any case dispatched to North Africa only to be inactivated and broken up. Suitable employment for the 1st Cavalry Division presented itself in the light of an experiment, and the solution adopted was to employ it as infantry. The division fought dismounted in the Southwest Pacific, under special tables of organization and equipment which raised it almost to the size of an infantry division. It retained the basic square formation of the cavalry division, and lacked the 155-mm howitzer battalion found in the infantry division, but was supplied with special allowances of heavy weapons and other equipment of infantry type. It should be noted that the single cavalry division included only a fraction of cavalry units in the Army, over 20,000 cavalrymen, all mechanized, being present in infantry and armored divisions, and almost 30,000 in non-divisional cavalry squadrons, chiefly mechanized.

The motorized division was adopted shortly after Pearl Harbor, with the intention that one be mobilized for each two armored divisions, the three to form a normal armored corps. The division in its short life went through various stages of planning, but in general it was conceived as an infantry division equipped organically with trucks for simultaneous movement without shuttling, and with large elements of reconnaissance, maintenance and supply to give it tactical independence. General McNair advised against the organization from the beginning, believing it wasteful to assign so much transportation organically, and preferring that improvements in infantry be made available to all infantry divisions alike.123

Five infantry divisions were ordered converted to motorized in 1942, and five more were planned for 1943, but in practice only the 4th Division was fully outfitted with the appropriate equipment, and it received so much additional equipment and personnel, over the established T/O, as to constitute a special task force. It was earmarked in August 1942 for overseas shipment. But it required so much ship tonnage (as much as an armored division without delivering the same punch) that no theater commander requested it in the following months.124 Even at T/O strength, the motorized division included almost 3,000 vehicles, over 1,000 more than the reduced infantry division as planned by the Army Ground Forces. Its tires consumed almost twice as many tons of rubber - 318 compared with 166. Its equipment required almost twice as much ocean tonnage, approximately 60,000 compared with 32,000. The motorized division was therefore viewed with extreme disfavor by the AGF Reduction Board. General McNair recommended its abolition.125

The question was not whether infantry should be motorized, but how motor vehicles should be organized to motorize it most effectively. Infantry could not fight from trucks; trucks were used only to put it into position for battle. It was desirable that a given number of trucks provide this form of mobility for a maximum number of troops. In 1936 the War Department, when planning to triangularize the division, had laid down the principle that motor transport for infantrymen should be pooled. General McNair clung to this principle. Shipping considerations now gave it added weight.

The standard infantry division was by no means immobile. All elements but the infantry were motorized. With its organic trucks the division could move in short bounds by shuttling, its trucks dumping their organic loads, moving the infantry, then returning to bring up the loads. As reduced by the Army Ground Forces in the months following November 1942, the division could move all personnel and equipment simultaneously if reinforced by six quartermaster truck companies each operating 48 2½-ton trucks. Six such companies, even with 48 1-ton trailers apiece, required only 15,000 ship tons, roughly half the difference between the standard infantry and the motorized infantry division. With a pool of such companies an army commander could operate

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flexibly, using the trucks to motorize infantry divisions at will, or for altogether different purposes if more urgent.

For a time the Operations Division, War Department General Staff, was unwilling to do away with the motorized division, believing it necessary as a means of giving infantry support to armored divisions. The decision to raise the infantry-tank ratio within the armored division reduced this need. OPD withdrew its objections on 18 February 1943, contingent upon reorganization of the armored division as proposed by the Army Ground Forces. All motorized divisions except the 4th were reconverted to standard infantry in March 1943.126

The Army Ground Forces, understanding from OPD that there was no prospective employment for a motorized division, requested permission to reconvert the 4th also.127 OPD decided that "the 4th Motorized Division should be maintained for the present as a nucleus of personnel trained for a function, the value of which has not been conclusively disproved."128 The European theater, queried on the subject, stated on 16 June 1943 that no motorized division was included in its plans for 1944, but that all infantry divisions should receive training in motor movement.129 The 4th Division was then reconverted. A standing operating procedure for motor movement of infantry divisions was developed by the Infantry School.130 Motor movement with attached trucks became a standard part of infantry division training.

Disappearance of the motorized division as a special unit was an incident in the reorganization of infantry and armored divisions. Its loss was not later regretted. Under stress of combat, units accomplished feats of transport not foreseen by the most economical planners. The 18th Infantry, during the rush across northern France in 1944, after having required 100 quartermaster trucks for the same job, found that it could move over thirty miles a day without additional transportation, remaining at all times in condition to fight, simply by piling infantrymen on the howitzers, tanks and tank destroyers attached to the regimental combat team.131 By similar improvised methods the entire 36th Division passed through the city of Rome in ten hours.132